1. Field of the Invention
The present invention relates to a seal device. More particularly, this invention relates to a seal device effecting a seal against a gap between assembly components whose clearance varies under the influence of fluid pressure, thermal deformation due to hot fluid, vibratory force during rotation or the like. This invention, for example, relates to a seal device effecting a seal between assembly components such as stator or shroud of gas turbine engines.
2. Description of the Related Art
Turbine assemblies include turbine sections of steam turbines and assembly unit of compressor and turbine sections of gas turbines or the like. Turbine section 100 of a gas turbine includes moving blade assembly 110 which rotates with a rotor and stationary blade assembly which is fixed in a compartment (not shown). The moving blade assembly 110 consists of a platform 110A which is connected to the rotor and moving blades 110B. The stationary blade assembly, on the other hand, consists of stationary blades, an inner shroud and an outer shroud wherein the inner shroud and the outer shroud are fixed at the both ends of the stationary blades.
A blade surface of the stationary blade and the inner and the outer shrouds form a passage wall for high temperature gas flowing through the turbine part, and also a blade surface of the moving blade 110B and the platform 110A form a passage wall for high temperature gas. Furthermore, in the compartment, a division ring forming a passage wall for high temperature gas together with the blade surface of the certain space between a tip end of the moving blade 110B. The provision ring is formed of a plurality of division ring sections that are connected in the direction of arrangement of moving blade 110B, and forms a wall surface of a circular ring cross section as a whole.
The moving blade assembly 110 as well as the stationary blade assembly need to be arranged to tolerate thermal deformation caused by heat passing through between the blades. Also mounting of a plurality of blades on the shroud section requires the fabrication process to be straightforward. In addition, division of the parts involved is necessary in order to simplify the assembly process and to decrease the associated assembly cost. For these reasons, the moving blade assembly 110 and the stationary blade assembly are divided into a plurality of subassemblies along the circumferential direction of the rotor. That is, the platform sections 110A as well as the shroud sections, like the division ring, are arranged to include a plurality of divided pieces which are adjoined in the direction of arrangement of blade.
As related art 1 of the present invention, US. Patent No. 2002/0090296A1 discloses a seal device, as depicted in FIG. 20. A turbine section 100 which forms a turbine passage wall of a gas turbine comprises a moving blade member, not shown, which rotates together with a rotor and a stationary blade member 110, not shown, fixed in a blade compartment. The moving blade member 110A consists of a platform 110A to be connected with an end portion of the rotor and a moving blade 110B. The stationary blade member consists of a stationary blade, not shown, and an inner shroud and an outer shroud fixed to each end of the stationary blade.
A blade surface of the stationary blade and the inner and the outer shrouds form a passage wall for high temperature gas V flowing through the turbine part. Also a blade surface of the moving blade 110B and the platform 110A form a passage wall for high temperature gas V. Furthermore, in the compartment, a division ring forming a passage wall for high temperature gas V together with the blade surface of the moving blade 110B and the platform 110A is fixed while interposing a certain space between a tip end of the moving blade 110B. The provision ring is formed of a plurality of division ring sections that are connected in the direction of arrangement of moving blade 110B, and forms a wall surface of a circular ring cross section as a whole.
The moving blade member 110 and the stationary blade member suffer from thermal deformation due to exposure to high temperature gas (sealed fluid) flowing through the blades. Such a structural inconvenience caused by the thermal deformation needs to be compensated by keeping a gap between the connected assembly surfaces. Also ease of manufacture for the shrouds needs to be taken into account because several blades are mounted onto the shrouds. Further, an assembly cost will increase unless ease of assembly is taken into consideration by dividing components in an appropriate manner. For these reasons, the moving blade member 110 and the stationary blade member are divided into a plurality of sections in the peripheral direction of the rotor. That is, the shroud and the platform 110A are arranged so that a plural number of shroud sections and platform sections are connected in the direction of arrangement of blade in the same manner as the division ring.
When the shroud, platform 110A and division ring are arranged in such a manner that the shroud sections, platform sections and division ring sections are, respectively, connected in the peripheral direction of the rotor, it is necessary to keep a gap between the connected shroud sections, between the connected platform sections, between the connected division ring sections for the reason of absorbing thermal deformation. The gap is so designed to allow a sufficient space such that heat expansion will not cause severe contact and damage of the adjacent surfaces. When the high temperature gas V flows through the passage which is formed by the blade surface, shroud, and platform 110A or division ring, the high temperature gas V needs to be prevented from leaking from the gap between the connected shroud sections and the like. When the high temperature gas V leaks outside from the gap, it may cause decrease in turbine efficiency, or occurrence of unexpected failure at other portions outside the fluid passage by the high temperature gas which is burned gas.
A mounting slot is provided in side end surfaces 113, 113 of the adjacent platforms 110A, 110A, and a sealing member 102 whose frontal view is an elongated T-bar shape is provided across the two mounting slots so as to prevent high temperature gas V from leaking outside from the gap 112. The sealing member 102 is also provided across the gap between the shroud sections as well as the gap between the division ring sections. With this T-bar sealing member 102, however, a certain gap inevitably remains between the adjacent platforms 110A, 110A unless the gap completely disappears after heat expansion brings the sealing member 102 and the two side end surfaces 113, 133 into seal-tight contact. Therefore, under an ordinary circumstance, high temperature gas V will leak outside from the gap. Also although the sealing member 102 in the figure has a straight form, manufacture of a curved sealing member will be difficult. Further, when the side end surfaces 113, 113 are subjected to heat expansion beyond tolerance, the surfaces collide with each other and give damage to the sealing member 102.
The present invention is introduced to resolve the above mentioned problems. Technical problem which the present invention tries to resolve is to improve seal ability of a seal device by maintaining seal contact of seal surfaces thereof even when external forces induced by thermal stress, fluid pressure, vibratory motion or the like cause to change a gap formed between both contact surfaces which mount the seal device therebetween. Another goal is to assure seal tight installation of the seal device even against an arcuate mount surface. Yet another goal is to make manufacture and installation of the seal device straightforward, and to reduce manufacture cost and assembly cost of the components.